The woman was hanging out with a group of people at the corner of Essex and Delancey streets at about 10:40 p.m. Friday when Takeam Brison, 32, approached them, police said.
Brison began shouting homophobic slurs at the group, telling them to "go back to f-----ville" and calling them "you lesbians, you homos," according to the Manhattan District attorney's criminal complaint.
When the woman intervened and asked why Brison would say that, Brison slashed the left side of her face, seriously injuring her, the NYPD said.
Brison ran away from the scene and called 911, telling the dispatcher that a group of homosexuals were following him, according to the criminal complaint.
Police arrested Brison and found a knife in his pocket, according to the complaint.
He was charged him with two counts of felony assault, including felony assault as a hate crime.
Brison's lawyer did not immediately respond to a request for comment.